Prepared Of Tungsten Carbide Loaded On Carbon Composite And Its Catalytic Performance

In recent years, tungsten carbide materials used in direct methanol fuel cells (DMFCs) as an alternative to the precious metal platinum is attracting more and more attention. Because of that the surface electronic structure of tungsten carbide is similar with that of platinum, tungsten carbide displays an interesting Pt-like catalytic property in some chemical and electrochemical reactions. However, the catalytic performance of tungsten carbide material is not as excellent as that of metal platinum. Therefore, the preparation of the tungsten carbide materials with high catalytic performance is becoming a hot spot of current research at home and abroad. Based on the investigations of recent development on tungsten carbide, two different methods were taken respectively to prepare the tungsten carbide loaded on carbon composite materials.On the one hand, the method of liquid phase transplantation was used, with ethanol as the dispersant, phosphotungstic acid (PTA) as the source of tungsten, mesoporous molecular sieve SB A-15and reamed ordered mesoporous carbon (OMC) CMK-3as the template and the carrier. By adjusting the dipping time, tungsten carbide loaded on carbon materials with large specific surface area, high catalytic activity were obtained through synchronous reduction and carbonization. The experimental results show that prepared mesoporous molecular sieve SBA-15with ethyl orthosilicate (TEOS) as SiO2precursor, P123as structure oriented agent has a neat and orderly channel and large specific surface area. The large pore diameter makes it easy to transfer tungsten source PTA into channel. The pore diameter of ordered mesoporous carbon materials CMK-3can also get to7-8nm after reaming, so more tungsten carbide can be loaded on ordered mesoporous carbon materials. The results of X-ray diffraction (XRD), cryogenic nitrogen gas stripping absorption (BET), X-ray energy spectrum (EDX) and field emission transmission electron microscope (TEM) characterization show that the composite material has a well-organized mesoporous structure, large specific surface area. Furthermore, both of the material showed good catalytic performance towards methanol electrooxidation in acid methanol solution.On the other hand, ion exchange method was used to parepare the WC/C material. The best carbonization process was concluded analyzing the thermo gravimetric curve and the infrared absorption curve of resin materials. Carbon load tungsten carbide WC/C composite material with large specific surface area was obtained through temperature programmed carbonization. The XRD, EDX, TEM and BET methods were used to characterize the phase structure; chemical composition and surface morphology of the composite material. Results showed that most of tungsten carbide in the WC/C material exist in the form of WC, WC dispersed evenly in the carbon substrate. The results of CV tests in neutral p-Nitrophenol solution show that the material has good catalytic ability towards the reduction of p-Nitrophenol. The WC/C composite material also has catalytic properties for methanol oxidation in acid methanol solution.